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Doubao Seed 1.8

doubaodoubao/doubao-seed-1-8

Doubao Seed 1.8 β€” incremental upgrade of Seed 1.6 with improved tool-call reliability.

ByteDance Seed β€” Seed1.8 announcement β†—Volcano Engine β€” Doubao models β†—GitHub β€” ByteDance-Seed/Seed-1.8 (Model Card + Cookbooks) β†—Seed1.8 Model Card (PDF) β†—

Doubao Seed 1.8 (Seed1.8) is ByteDance's general-purpose agentic model released December 18, 2025. It extends the Seed family with unified search, code, and GUI agent capabilities while retaining strong base LLM and VLM performance. The model supports three configurable thinking modes that let operators trade latency for depth on a per-request basis.

For TheRouter operators, Seed 1.8 is the strongest Chinese-language generalist agent option in the mid-tier price band. It leads or matches top models on BrowseComp-en (67.6) and shows robust real-world agentic coding and GUI performance. The model is fully OpenAI-compatible through api.therouter.ai/v1 and is the direct predecessor to the Seed 2.0 family released February 2026.

Best for
  • β€’ Chinese-language agentic workflows that combine tool use, web search, and GUI interaction where cost-effective mid-tier pricing is required.
  • β€’ Complex instruction following and multi-step task execution in Chinese enterprise or consumer applications.
Reach for something else if
  • β€’ Pure English reasoning or code tasks where DeepSeek-V3.2 or Claude Sonnet 4.6 deliver higher measured throughput and benchmark scores.
  • β€’ Video or heavy multimodal workloads β€” TheRouter currently exposes Seed 1.8 via text-only chat completions (see standard-models.yaml modalities).
Context Length
131K
Max Output
33K
Input Priceper 1M tokens
$0.270/ 1M tokens
Output Priceper 1M tokens
$2.16/ 1M tokens

Modalities

text→text

Pricing Breakdown

TypeRate
Input$0.270 / 1M tokens
Output$2.16 / 1M tokens

Supported Parameters

temperaturemax_tokenstop_ptoolstool_choiceresponse_formatstop

Specifications

Release date2025-12-18seed.bytedance.com β†—verified
ArchitectureUnified agentic model with native vision (text + image input)github.com β†—verified
Thinking modesThree configurable modes for latency vs. depth trade-offseed.bytedance.com β†—verified
Training cutoffNot publicly disclosedunknown
LicenseApache 2.0 (weights & code)github.com β†—verified

Benchmarks

BenchmarkDistributionScoreSource
BrowseComp-en
Top-tier agentic search benchmark; exceeds Gemini-3-Pro in public comparisons.
67.6seed.bytedance.com β†—
ZeroBench
Visual reasoning benchmark; significant improvement over Seed 1.5-VL predecessor.
11.0seed.bytedance.com β†—
VideoMME
Long-video understanding; strong results but not currently exposed via TheRouter text-only endpoint.
87.8seed.bytedance.com β†—
WorldTravel
Real-world multimodal travel-planning agent task; best-of-5 scoring.
47.2seed.bytedance.com β†—

API Usage Examples

Use the global api.therouter.ai endpoint shown below for new integrations; the legacy China accelerated endpoint is retired.

cURL
curl https://api.therouter.ai/v1/chat/completions   -H "Content-Type: application/json"   -H "Authorization: Bearer $THE_ROUTER_API_KEY"   -d '{
    "model": "doubao/doubao-seed-1-8",
    "messages": [
      {"role": "user", "content": "Summarize the key points from this input."}
    ]
  }'

API guide

Full API reference β†’

Chat completion

cURL
curl https://api.therouter.ai/v1/chat/completions \
  -H "Authorization: Bearer $THEROUTER_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"model":"doubao/doubao-seed-1-8","messages":[{"role":"user","content":"η”¨δΈ­ζ–‡θ§£ι‡Š Seed 1.8 ηš„δΈ‰η§ζ€θ€ƒζ¨‘εΌγ€‚"}]}'

More from doubao

doubao/doubao-seed-2-0-proDirect successor in the Seed 2.0 family; higher capability tier.doubao/doubao-seed-2-0-liteCost-efficient sibling in the Seed 2.0 family for high-volume traffic.doubao/doubao-seed-1-6Immediate predecessor; useful for A/B testing or cost-sensitive fallback.

Similar models

Cross-provider sibling models
deepseek/deepseek-v3.2
Open-weight peer with strong English + code performance; useful cross-provider fallback.
qwen/qwen3-235b
Same parameter class, strong multilingual baseline; good routing pair for Chinese vs English traffic.
anthropic/claude-sonnet-4.6
Premium English agentic model; useful for tiered routing when budget allows.
tencent/hunyuan-a13b
Another Chinese-provider MoE; useful for provider diversity and latency triangulation.

News & changes

2025-12-18

ByteDance releases Seed1.8 general agentic model

ByteDance Seed team launched Seed1.8, a unified agentic model integrating search, code, and GUI capabilities with three thinking modes. The release emphasizes real-world workflow evaluation and token-efficient visual encoding. Seed1.8 is the direct predecessor to the Seed 2.0 family.

re-authored by TheRouterseed.bytedance.com β†—
2026-02-14

ByteDance launches Seed 2.0 family, superseding Seed 1.8

The Seed 2.0 lineup (pro, lite, mini, code) was released as the production successor to Seed 1.8. Seed 1.8 remains available for existing workloads and cost-sensitive routing tiers.

re-authored by TheRoutervolcengine.com β†—

Frequently asked

Is Doubao Seed 1.8 multimodal?

The underlying Seed 1.8 model supports text + image input and strong video understanding. However, TheRouter currently exposes it via the text-only chat completions endpoint per the modality declaration in standard-models.yaml. Image and video capabilities are not currently routed through TheRouter for this model.

re-authored by TheRouterseed.bytedance.com β†—
What are the three thinking modes in Seed 1.8?

Seed 1.8 provides three configurable thinking modes that let the model automatically or explicitly adjust inference depth versus latency. This enables cost/latency-aware routing: simple queries can use the fastest mode while complex agentic workflows can request deeper reasoning.

re-authored by TheRouterseed.bytedance.com β†—
Fact ledger β€” every claim on this page traces here
sourceURLretrieved
Release dateseed.bytedance.com β†—2026-05-25verified
Architecturegithub.com β†—2026-05-25verified
Thinking modesseed.bytedance.com β†—2026-05-25verified
Training cutoffβ€”β€”unknown
Licensegithub.com β†—2026-05-25verified
BrowseComp-enseed.bytedance.com β†—2026-05-25verified
ZeroBenchseed.bytedance.com β†—2026-05-25to verify
VideoMMEseed.bytedance.com β†—2026-05-25to verify
WorldTravelseed.bytedance.com β†—2026-05-25to verify
ByteDance releases Seed1.8 general agentic modelseed.bytedance.com β†—2026-05-25verified
ByteDance launches Seed 2.0 family, superseding Seed 1.8volcengine.com β†—2026-05-25verified
Is Doubao Seed 1.8 multimodal?seed.bytedance.com β†—2026-05-25to verify
What are the three thinking modes in Seed 1.8?seed.bytedance.com β†—2026-05-25to verify
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